Wigan boss Roberto Martinez was left fuming after his ten-men went down 5-0 to Manchester United.
The game turned on Connor Sammon's red card when United were just a goal ahead towards the end of the first half. Sammon stuck out his arm to try and shield possession, caught Michael Carrick in the face and Phil Dowd promptly sent him off.
"The red card is a shocking decision," said Martinez. "There was a little bit of a fight, as there was every time the two players went for the ball. None of them should have been a red card. None of them were malicious. There was no intent."
He added: "If you want to show a red card using those standards, do it, then you will end up with six men each.
"Anyone who has been on a football pitch knows that incident was a normal action. I was surprised when he gave the free-kick. To see the red card, I was gobsmacked."
Even Ferguson admitted it was "harsh" but his side took full advantage.
Park Ji-sung had already put the hosts in front and within two minutes of Sammon's exit, Dimitar Berbatov added another, by using tactics Martinez felt were similar to that his own side were punished for.
United cut loose after the interval, with Berbatov adding another followed by an effort from former Wigan man Antonio Valencia.
Making only his second Premier League start of the season, Berbatov wrapped things up with a penalty after Wayne Rooney had stood aside following Antolin Alcaraz's foul on Park, which seemed to take place outside the box.
"It was the right game for Dimitar," said Ferguson. "I needed his height in terms of set-piece play against us and he weighed in with a hat-trick. We are really pleased for him. It helps his confidence. He has not had the best start to the season in terms of selection because of the options I have, with (Danny) Welbeck, (Wayne) Rooney and (Javier) Hernandez."